"Yesterday I was at home."
Translation:Tegnap otthon voltam.
Ok native speakers tell me why not, "Tegnap itthon voltam" i.e. you were at home yesterday still and are?
No reason, it should be accepted. The only condition for saying "itthon" is that you say it while being at home.
"Itthon" is actually something like "here-home", while "otthon" is "there-home". You only say "itthon" for your own home and only when you are in your home.